London will welcome 200 black cabs run on alternative fuel in time for the 2012 Olympic Games.

Powered by hydrogen fuel cells, the cabs are being developed by Intelligent Energy, Lotus, TRW Conekt and LTI (London Taxis International), the Environmental Transport Association (ETA) reports.

In order to allow the vehicles to be properly integrated into the city five hydrogen filling stations are to be provided in time for the Games.

Air Products will launch the mobile trailer-mounted refuelling units, which can be parked on the forecourts of regular fuel stations.

By using these mobile systems the infrastructure for the hydrogen-powered cabs can remain relatively cheap and quick to implement.

Commenting on the ETA's website, a spokesperson from the association said: "A London TX4 taxi emits 226g CO2 per km, but the problem with diesel-engined vans, buses and cabs in urban areas is more about the particulates released in their exhaust. The detrimental effect this has on health makes a strong case for switching to fuel cell technology."

The group added that these new cabs will emit no emissions during use.